Hi, I got a vintage mug (Islander 3 face tiki mug from Stockton, CA) on eBay. The description said it had some water stains. Well, I'm pretty sure they're not water stains.

There is a ring on the inside of the mug of some sticky, sappy substance. No amount of dish detergent or bleach (Clorox Cleanup) will take it off. This substance is also on the outside of the mug. You can feel it, but you can't really see it very well, so there isn't much, but it is very resistant to cleaning.

I was going to try degreaser and/or paint thinner, but I wanted to ask here first what you all thought. I don't want to damage the finish on the mug.
_________________Liquor and Drink

Wiping the area with mineral spirits should take off the residue without any issues as long as there is no loose cold paint, stickers, or the like which could be removed in the process. Likewise, "Goof-Off" or the equivalent de-gunking product will do much the same.

I've used GOO GONE with some success. It takes off most marker, gunk, candle wax. There have been some ring stains that it doesn't seem to work on though. You need to let the GOO GONE sit on the problem spot for a minute or so, then rub out with a paper towel.

With the disclaimer that I haven't used them on a vintage mug, Mr. Clean Magic Erasers (or the generic/store-brand version) are fantastic at removing stains. They'll take old, stubborn tea stains off my mugs in pretty much one swipe. I've tried them on all sorts of different stains & smudges, even some gunky messes around the house and they've always worked really well. They don't need soap added, just water.

I just got a mug that had some disgusting rust-like substance inside on the bottom. It was as if nothing would remove the crud, no matter how much washing I did. After letting it soak with dish suds and hot water for a few days I ended up using a brillo pad. I used a knife to push the brillo pad down securely and spun it around multiple times, while rinsing w/ hot water. After a few tries (actually about 10 solid minutes) I was able to clean it up. I havent tried a brillo on the outside of a mug so I cant recommend that.
_________________Make mine a mai tai!

"I just wanted to comment on the use of CLR in your home. DO NOT DO IT! My brother (who was 23 at the time) moved a piece of equipment that had been cleaned with CLR and unknowingly got a tiny bit of CLR on a cut on his finger. Within a few hours, he had bizarre symptoms which persisted through the evening. My parents took him to the ER and at first they thought he might have meningitis and quarantined him. Ultimately, he ended up in Intensive Care for one week, he went from a very muscular 155 pound man to a skeletal 110. He actually died twice, but they were able to revive him. The reports came back pointing to CLR, he had gone into toxic shock from it. DO NOT USE THIS STUFF IN YOUR HOME WITH ANYTHING THAT WILL COME IN CONTACT WITH ANYONE! My brother is very lucky to be alive. The doctors told him that he will have heart issues later in life due to the stress that he endured with his heart rate being elevated for so long (he had a 180+ heart rate for 4 days straight).
http://answers.yahoo.com/question/index;_ylt=Ap_MHg9YQ.0XxWxHP21fnW5_6xR.;_ylv=3?qid=20080206193411AAbjztp

"I just wanted to comment on the use of CLR in your home. DO NOT DO IT! My brother (who was 23 at the time) moved a piece of equipment that had been cleaned with CLR and unknowingly got a tiny bit of CLR on a cut on his finger. Within a few hours, he had bizarre symptoms which persisted through the evening. My parents took him to the ER and at first they thought he might have meningitis and quarantined him. Ultimately, he ended up in Intensive Care for one week, he went from a very muscular 155 pound man to a skeletal 110. He actually died twice, but they were able to revive him. The reports came back pointing to CLR, he had gone into toxic shock from it. DO NOT USE THIS STUFF IN YOUR HOME WITH ANYTHING THAT WILL COME IN CONTACT WITH ANYONE! My brother is very lucky to be alive. The doctors told him that he will have heart issues later in life due to the stress that he endured with his heart rate being elevated for so long (he had a 180+ heart rate for 4 days straight).
http://answers.yahoo.com/question/index;_ylt=Ap_MHg9YQ.0XxWxHP21fnW5_6xR.;_ylv=3?qid=20080206193411AAbjztp

Yikes!

Ummm... I don't really think so...

True, it does say to wear gloves while using it, but I was using CLR on my truck just last week (I'd inadvertantly parked under a drippy, rusty pipe a while back and rec'd a bunch of rust stains on the hood) when I accidentally knocked the bottle over and pretty much soaked myself with it. All over both arms, hands, legs & feet. Soaked through my shorts & socks - I was swimming in it, practically. Wiped it all off with some paper towels and kept working. No big deal. I didn't die, not even once. In fact, it didn't even burn or cause any amount of discomfort, other than wasting most of the bottle of CLR. Maybe the guy in the story above has some bizzarro CLR allergy or something. (Or else I have some even-more-bizzarro CLR immunity!! I wonder what kind of cocktail I can mix with CLR? Hmmm...)

"I just wanted to comment on the use of CLR in your home. DO NOT DO IT! My brother (who was 23 at the time) moved a piece of equipment that had been cleaned with CLR and unknowingly got a tiny bit of CLR on a cut on his finger. Within a few hours, he had bizarre symptoms which persisted through the evening. My parents took him to the ER and at first they thought he might have meningitis and quarantined him. Ultimately, he ended up in Intensive Care for one week, he went from a very muscular 155 pound man to a skeletal 110. He actually died twice, but they were able to revive him. The reports came back pointing to CLR, he had gone into toxic shock from it. DO NOT USE THIS STUFF IN YOUR HOME WITH ANYTHING THAT WILL COME IN CONTACT WITH ANYONE! My brother is very lucky to be alive. The doctors told him that he will have heart issues later in life due to the stress that he endured with his heart rate being elevated for so long (he had a 180+ heart rate for 4 days straight).
http://answers.yahoo.com/question/index;_ylt=Ap_MHg9YQ.0XxWxHP21fnW5_6xR.;_ylv=3?qid=20080206193411AAbjztp

Yikes!

Ummm... I don't really think so...

True, it does say to wear gloves while using it, but I was using CLR on my truck just last week (I'd inadvertantly parked under a drippy, rusty pipe a while back and rec'd a bunch of rust stains on the hood) when I accidentally knocked the bottle over and pretty much soaked myself with it. All over both arms, hands, legs & feet. Soaked through my shorts & socks - I was swimming in it, practically. Wiped it all off with some paper towels and kept working. No big deal. I didn't die, not even once. In fact, it didn't even burn or cause any amount of discomfort, other than wasting most of the bottle of CLR. Maybe the guy in the story above has some bizzarro CLR allergy or something. (Or else I have some even-more-bizzarro CLR immunity!! I wonder what kind of cocktail I can mix with CLR? Hmmm...)

Yeah, if it is even true, it would have to be the combination of the guy being allergic to it and the "fact" that he got the stuff into his bloodstream via the cut on his finger. Still, getting stuff like CLR on your skin and getting CLR into your bloodstream are two very different things.

What surfaces should I not use CLR on?
DO not use CLR on natural stone or marble, terrazzo, colored grout, painted or metallic glazed surfaces, plastic laminates, Formica, aluminum, steam irons, leaded crystal, refinished tubs or any damaged or cracked surface. CLR may etch older sinks, tubs and tiles. CLR is corrosive. Avoid contact with wood, clothing, wallpaper and carpeting. Some laminated surfaces (counter tops) are coated with a synthetic surface which may be affected by rust removers; clean spills immediately.